Supplemental write cache command for bandwidth compression

ABSTRACT

Aspects include computing devices, systems, and methods for implementing a cache memory access requests for data smaller than a cache line and eliminating overfetching from a main memory by writing supplemental data to the unfilled portions of the cache line. A cache memory controller may receive a cache memory access request with a supplemental write command for data smaller than a cache line. The cache memory controller may write supplemental to the portions of the cache line not filled by the data in response to a write cache memory access request or a cache miss during a read cache memory access request. In the event of a cache miss, the cache memory controller may retrieve the data from the main memory, excluding any overfetch data, and write the data and the supplemental data to the cache line. Eliminating overfetching reduces bandwidth and power required to retrieved data from main memory.

RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.14/467,773 entitled “Power Aware Padding”, which is filedcontemporaneously with this application and is hereby incorporated byreference in its entirety.

BACKGROUND

Lossless compression is used in systems as a way to reduce the amount ofdata that has to be read from or written back to a main memory.Compression works on segments of input data, typically of fixed size,which are compressed into smaller block sizes. Lossless compressions usesegments of configurable sizes. An example would be compressing 256 bytesegments into 64 byte blocks, 128 byte blocks, 192 byte blocks, or 256byte blocks depending on the compression rate that the algorithm canachieve. This compressed data would then be stored in caches until it iswritten back to the main memory. Due to the nature of compression therecan be unused holes in a physical address space of the cache. Theseholes can occur within a cache line. When the data is propagated througha cache with a larger cache line than the smallest compressed sizemultiple, overfetch of data from the cache to the main memory results.

When requesting a small sized block of data from the cache, the cachemust fill the entire line, but due to the holes in compressed data, onlya portion of that line will contain useful data as the holes in thecache line will be filled with irrelevant data. This results inoverfetching by the cache to a main memory with part of the overfetchbeing garbage. For example if a segment is compressed to 64 bytes or 192bytes and requested from a cache with 128 byte lines, then an extra 64bytes of useless data will be loaded to the cache in each case to fillthe hole in the cache line. In a good compression scheme, a largefraction of the compressed blocks will be the smallest size.Consequently the benefits of bandwidth compression are diminished andneedless power is consumed fetching unnecessary data and writing backthat random data.

SUMMARY

The methods and apparatuses of various aspects provide circuits andmethods for executing cache memory access requests for data on acomputing device, may include receiving a cache memory access requestfor data smaller than a cache line to which the data is addressed in thecache memory access request, receiving a supplemental write commandassociated with the received cache memory access request, and writingsupplemental data to unfilled portions of the cache line to which thedata is addressed in the cache memory access request.

An aspect method may further include determining whether the data islocated in the cache line to which the data is addressed in the cachememory access request, retrieving the data from a memory in response todetermining that the data is not located in the cache line to which thedata is addressed, writing the data to the cache line to which the datais addressed resulting in unfilled portions of the cache line, andignoring a dirty bit of the cache line.

In an aspect, receiving the supplemental write command associated withthe received cache memory access request may include receiving aninstruction directing a cache memory controller to write supplementaldata to unfilled portions of the cache line.

In an aspect, receiving the supplemental write command associated withthe received cache memory access request may include receiving a signalindicating the supplemental write command, and interpreting the signalby a cache memory controller causing the cache memory controller towrite supplemental data to unfilled portions of the cache line.

In an aspect writing supplemental data to unfilled portions of the cacheline to which the data is addressed in the cache memory access requestmay include writing one of constant data values to unfilled portions ofthe cache line to which the data is addressed.

In an aspect, writing supplemental data to unfilled portions of thecache line to which the data is addressed in the cache memory accessrequest may include writing a pattern of data values to unfilledportions of the cache line to which the data is addressed.

In an aspect writing supplemental data to unfilled portions of the cacheline to which the data is addressed in the cache memory access requestmay include writing random values to unfilled portions of the cache lineto which the data is addressed.

An aspect includes a computing device having a processor, a cache memorycontroller, a cache memory, a memory controller, and a memorycommunicatively connected to each other in which the cache memorycontroller are configured to perform operations of one or more of theaspect methods described above.

An aspect includes a non-transitory processor-readable medium havingstored thereon processor-executable instructions configured to cause aprocessor and a cache memory controller to perform operations of one ormore of the aspect methods described above.

An aspect includes a computing device having means for performingfunctions of one or more of the aspect methods described above.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitutepart of this specification, illustrate example aspects of the invention,and together with the general description given above and the detaileddescription given below, serve to explain the features of the invention.

FIG. 1 is a component block diagram illustrating a computing devicesuitable for implementing an aspect.

FIG. 2 is a component block diagram illustrating an example multi-coreprocessor suitable for implementing an aspect.

FIG. 3 is a component block diagram illustrating an example system onchip (SoC) including a cache memory controller configured to implementsupplemental write cache commands in accordance with an aspect.

FIG. 4 is an illustration of a portion of a cache memory including acache line storing compressed data in accordance with an aspect.

FIG. 5 is an illustration of a portion of a cache memory including acache line storing compressed data in accordance with an aspect.

FIG. 6 is process and signals flow diagram of a read cache memory accessrequest with supplemental write command for retrieving compressed datafrom a cache memory in accordance with an aspect.

FIG. 7 is process and signals flow diagram of a write cache memoryaccess request with supplemental write command for writing compresseddata to a cache memory in accordance with an aspect.

FIG. 8 is process and signals flow diagram of a write cache memoryaccess request with power aware padding for writing compressed data to acache memory in accordance with an aspect.

FIG. 9 is a process flow diagram illustrating an aspect method forimplementing cache memory access requests with supplemental writecommand for compressed data.

FIG. 10 is a process flow diagram illustrating an aspect method forimplementing cache memory access requests with power aware padding forcompressed data.

FIG. 11 is component block diagram illustrating an example mobilecomputing device suitable for use with the various aspects.

FIG. 12 is component block diagram illustrating an example mobilecomputing device suitable for use with the various aspects.

FIG. 13 is component block diagram illustrating an example serversuitable for use with the various aspects.

DETAILED DESCRIPTION

The various aspects will be described in detail with reference to theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.References made to particular examples and implementations are forillustrative purposes, and are not intended to limit the scope of theinvention or the claims.

The terms “computing device” and “mobile computing device” are usedinterchangeably herein to refer to any one or all of cellulartelephones, smartphones, personal or mobile multi-media players,personal data assistants (PDA's), laptop computers, tablet computers,smartbooks, ultrabooks, palm-top computers, wireless electronic mailreceivers, multimedia Internet enabled cellular telephones, wirelessgaming controllers, and similar personal electronic devices that includea memory, and a multi-core programmable processor. While the variousaspects are particularly useful for mobile computing devices, such assmartphones, which have limited memory and battery resources, theaspects are generally useful in any electronic device that implements aplurality of memory devices and a limited power budget in which reducingthe power consumption of the processors can extend the battery-operatingtime of the mobile computing device.

The term “system-on-chip” (SoC) is used herein to refer to a set ofinterconnected electronic circuits typically, but not exclusively,including a hardware core, a memory, and a communication interface. Ahardware core may include a variety of different types of processors,such as a general purpose processor, a central processing unit (CPU), adigital signal processor (DSP), a graphics processing unit (GPU), anaccelerated processing unit (APU), an auxiliary processor, a single-coreprocessor, and a multi-core processor. A hardware core may furtherembody other hardware and hardware combinations, such as a fieldprogrammable gate array (FPGA), an application-specific integratedcircuit (ASCI), other programmable logic device, discrete gate logic,transistor logic, performance monitoring hardware, watchdog hardware,and time references. Integrated circuits may be configured such that thecomponents of the integrated circuit reside on a single piece ofsemiconductor material, such as silicon.

Aspects include methods and computing devices implementing such methodsfor eliminating overfetching to a main memory by a cache by writing datavalues (e.g., all “0”s) to the portions of the cache line not filledwith compressed data. Such aspects include a new supplemental writecommand that fills in the rest of the cache line.

Data values may be written to the cache by a cache memory controllerwhen requesting the compressed data from the main memory. A cache memorycontroller receiving the hybrid read cache memory access request withthe supplemental write command may perform a read of compressed datasmaller than a cache line, and when the compressed data is not in thecache (a cache miss), may retrieve the compressed data from main memoryand write supplemental data (e.g., “0” or “1”) to fill out the unusedportions of the cache line. For example, if a READ request from theprocessor for 64 bytes of compressed data from the cache with 128 bytecache lines results in a cache miss, the cache memory controller mayallocate a cache line containing the address for the requestedcompressed data and request the compressed data from the main memory.This request to the main memory may be for only the compressed dataregardless of the size of the cache line. Thus, the request for thecompressed data from the cache memory controller may be for a block ofcompressed data smaller than the cache line. In response to such arequest the cache memory controller may write the compressed dataretrieved from the main memory to the allocated cache line. As part ofthis write process, the cache memory controller may also writesupplemental data, such as all 0's (or 1's), to the remaining portionsof the cache line. For example, when writing 64 bytes of compressed datato the cache line of 128 bytes, the remaining 64 bytes of the cache linemay be filled with supplemental data. Similarly, the cache memorycontroller may set the remaining portions of the cache line to thesupplemental data in response to a WRITE request from the processor towrite compressed data to the cache.

Eliminating retrieval of data from the main memory to fill out theunused portions of the cache line by requesting only the compressed dataand filling in unused portions of the cache line with supplemental dataeliminates overfetching from the main memory. Thus, the bandwidth andpower required to retrieve data from the main memory is reduced becauseless data is passed between the main memory and the cache.

Aspects include methods and computing devices implementing such methodsfor writing padding data, such as all 0's (or all 1's), to the cache aspart of padded compression data received by the cache from theprocessor. This enables the processor to compress a block of data to asize smaller than a cache line and add padding data to the compresseddata to fill out the portions of the cache line that will not be filledwith the compressed data. The processor may send a data packet,including the compressed data and the padding data, in a write requestto the cache. In an example, when the compressed data is 64 bytes andthe cache line is 128 bytes, the processor may add 64 bytes of paddingdata to the 64 bytes of compressed data so that the compressed data plusthe padding make up a 128 byte data packet. The cache memory controllermay receive the data packet and write the data packet to a cache line ata location designated in the write request. Writing the data packet tothe cache line fills the cache line with the compressed data and thepadding data. When the cached compressed data is copied to the mainmemory, it may similarly be stored with the padding data in the cacheline. When the cached compressed data is retrieved from the main memory,it may similarly be retrieved with the padding data to fill the cacheline.

Filling out the portions of the cache line not designated to store thecompressed data by writing the compressed data combined with the paddingdata eliminates overfetching from the main memory. The data is the samesize as the cache line, thus when retrieving the compressed data fromthe main memory, it will include the padding data and no irrelevant dataneeds to be retrieved from the main memory to fill in missing data inthe cache line. Also, power required to retrieve padding data, such as aseries of all 0's (or all 1's), is less than the power required toretrieve varying values from the main memory.

For ease of description, the various aspects may be described in termsof their use with compressed data; however, the aspects may be used forany data that does not completely fill a cache line.

FIG. 1 illustrates a system including a computing device 10 incommunication with a remote computing device 50 suitable for use withthe various aspects. The computing device 10 may include an SoC 12 witha processor 14, a memory 16, a communication interface 18, and a storageinterface 20. The computing device may further include a communicationcomponent 22 such as a wired or wireless modem, a storage component 24,an antenna 26 for establishing a wireless connection 32 to a wirelessnetwork 30, and/or the network interface 28 for connecting to a wiredconnection 44 to the Internet 40. The processor 14 may include any of avariety of hardware cores, as well as a number of processor cores. TheSoC 12 may include one or more processors 14. The computing device 10may include more than one SoCs 12, thereby increasing the number ofprocessors 14 and processor cores. The computing device 10 may alsoinclude processor 14 that are not associated with an SoC 12. Individualprocessors 14 may be multi-core processors as described below withreference to FIG. 2. The processors 14 may each be configured forspecific purposes that may be the same as or different from otherprocessors 14 of the computing device 10. One or more of the processors14 and processor cores of the same or different configurations may begrouped together.

The memory 16 of the SoC 12 may be a volatile or non-volatile memoryconfigured for storing data and processor-executable code for access bythe processor 14. In an aspect, the memory 16 may be configured to storedata at least temporarily, such as compressed processing data output byone or more of the processors 14. In an aspect, the memory 16 may beconfigured to store information for cache memory access request forcompressed data using a supplemental write command or power awarepadding. The memory 16 may include non-volatile read-only memory (ROM)in order to retain the compressed data accessible by a processor 14and/or a cache memory controller (as show in FIG. 3).

The computing device 10 and/or SoC 12 may include one or more memories16 configured for various purposes. In an aspect, one or more memories16 may be configured to be dedicated to storing the compressed data foraccess by specific processors 14 and/or cache memory controllers. Thememory 16 may store the compressed date in a manner that enables thecompressed data to be accessed by the processor 14 and/or the cachememory controller for implementing cache memory access requests forcompressed data using a supplemental write command or power awarepadding.

The communication interface 18, communication component 22, antenna 26,and/or network interface 28, may work in unison to enable the computingdevice 10 to communicate over a wireless network 30 via a wirelessconnection 32, and/or a wired network 44 with the remote computingdevice 50. The wireless network 30 may be implemented using a variety ofwireless communication technologies, including, for example, radiofrequency spectrum used for wireless communications, to provide thecomputing device 10 with a connection to the Internet 40 by which it mayexchange data with the remote computing device 50.

The storage interface 20 and the storage component 24 may work in unisonto allow the computing device 10 to store data on a non-volatile storagemedium. The storage component 24 may be configured much like an aspectof the memory 16 in which the storage component 24 may store thecompressed data, such that information may be accessed by one or moreprocessors 14 and/or cache memory controllers. The storage component 24,being non-volatile, may retain the information even after the power ofthe computing device 10 has been shut off. When the power is turned backon and the computing device 10 reboots, the information stored on thestorage component 24 may be available to the computing device 10. Thestorage interface 20 may control access to the storage device 24 andallow the processor 14 to read data from and write data to the storagedevice 24.

Some or all of the components of the computing device 10 may bedifferently arranged and/or combined while still serving the necessaryfunctions. Moreover, the computing device 10 may not be limited to oneof each of the components, and multiple instances of each component maybe included in various configurations of the computing device 10.

FIG. 2 illustrates a multi-core processor 14 suitable for implementingan aspect. The multi-core processor 14 may have a plurality ofhomogeneous or heterogeneous processor cores 200, 201, 202, 203. Theprocessor cores 200, 201, 202, 203 may be homogeneous in that, theprocessor cores 200, 201, 202, 203 of a single processor 14 may beconfigured for the same purpose and have the same or similar performancecharacteristics. For example, the processor 14 may be a general purposeprocessor, and the processor cores 200, 201, 202, 203 may be homogeneousgeneral purpose processor cores. Alternatively, the processor 14 may bea graphics processing unit or a digital signal processor, and theprocessor cores 200, 201, 202, 203 may be homogeneous graphics processorcores or digital signal processor cores, respectively. For ease ofreference, the terms “processor” and “processor core” may be usedinterchangeably herein.

The processor cores 200, 201, 202, 203 may be heterogeneous in that, theprocessor cores 200, 201, 202, 203 of a single processor 14 may beconfigured for different purposes and/or have different performancecharacteristics. Example of such heterogeneous processor cores mayinclude what are known as “big.LITTLE” architectures in which slower,low-power processor cores may be coupled with more powerful andpower-hungry processor cores.

In the example illustrated in FIG. 2, the multi-core processor 14includes four processor cores 200, 201, 202, 203 (i.e., processor core0, processor core 1, processor core 2, and processor core 3). For easeof explanation, the examples herein may refer to the four processorcores 200, 201, 202, 203 illustrated in FIG. 2. However, the fourprocessor cores 200, 201, 202, 203 illustrated in FIG. 2 and describedherein are merely provided as an example and in no way are meant tolimit the various aspects to a four-core processor system. The computingdevice 10, the SoC 12, or the multi-core processor 14 may individuallyor in combination include fewer or more than the four processor cores200, 201, 202, 203 illustrated and described herein.

FIG. 3 illustrates an example SoC 12 including a cache memory controller300 and a cache memory 302 configured to store data, includingcompressed data and data smaller than a cache line, from and allowaccess to the data by requesting processors 14, including individualprocessor cores. The SoC 12 may also include a memory controller 304,the memory 16, and other components such as the components of the SoC 12described above. The cache memory 302 may be configured to temporarilystore data and program instructions for quicker access than whenaccessing the storage component 24 in FIG. 1 or the memory 16. 1. Thecache memory 302 may be dedicated for use by a single processor 14 orshared between multiple processors 14. In an aspect, the cache memory306 may be part of the processor 14, and may be dedicated for use by asingle processor core or shared between multiple processor cores of theprocessor 14.

The cache memory controller 300 may manage access to the cache memory302 by various processors 14 and subsystems (not shown) of the SoC 12.The cache memory controller 300 may also manage memory access requestsfor access from the cache memory controller 300 to the memory 16 forretrieving data that may be requested from the cache memory 302 by theprocessor 14, but not found in the cache memory 302. Part of the accessmanagement of the cache memory may include implementing a supplementalwrite command according to various aspects for write and read cachememory access requests issued by the processor 14 to the cache memory302 for compressed data. Supplemental write commands may be used forcache memory access requests for compressed data that has a size or acompression ratio such that the compressed data may not fill a cacheline.

For a write or read cache memory access request for compressed data, thecache memory controller 304 may receive, as part of or separate from thecache memory access request, a supplemental write command issued by theprocessor 14. In an aspect, the supplemental write command may be a newsignal developed for indicating the supplemental write command,including a new instruction, a persistent field(s) included in the cachememory access request, or part of a communication message associated tothe cache memory access request. The signal may contain instructions forinstructing the cache memory controller 304 to implement resulting in asupplemental write command. In an aspect, the cache memory controller304 may be configured to implement a supplemental write command and torecognize a signal configured to trigger the cache memory controller 304to execute a supplemental write command. The signal may be an existingsignal and the cache memory controller 300 may be configured to identifythe existing signal to trigger a supplemental write command. In anaspect, the cache memory controller 304 may be configured to identifywhen the cache memory access request is for compressed data of aparticular size, compression ratio and/or location, and determinewhether to execute the supplemental write command.

The supplemental write command may be implemented for any write cachememory access request for compressed data when the compressed data maynot fill the one or more cache lines that it is addressed to occupy. Thesupplemental write command may be implemented for any read cache memoryaccess request for compressed data in which the compressed data is notfound in a cache line designated by the address of the cache memoryaccess request (e.g. a cache miss). The compressed data may be retrievedfrom the memory 16 and written to the cache memory 302. The supplementalwrite command may be implemented for the read cache memory accessrequest when the compressed data written to the cache memory 302 fromthe memory 16 may not fill the one or more cache lines it is addressedto occupy.

As will be discussed in more detail below, the data received from theprocessor 14 and the memory 16 for writing to the cache memory 302 mayinclude only the compressed data, regardless of whether the compresseddata fills the one or more cache lines it is addressed to occupy. Thesupplemental write command may be configured to write data values toportions of the cache line(s) written to for storing the compresseddata, but not filled by the compressed data. The supplemental writecommand may cause the cache memory controller 300 to fill the remainingportions of the cache line(s) with supplemental data values that may beconstant values or a pattern of values. In an aspect, the supplementalwrite command may cause the cache memory controller 300 to fill theremaining portions of the cache line(s) with random data values.

Receiving only the compressed data from the memory 16 reduces thebandwidth necessary to transmit the compressed data between thecomponents of the computing device. Traditionally compressed data fromthe memory 16 may be received as part of a transaction that alsoincludes overfetch data. The overfetch data may include random datavalues that are added to the compressed data to fill in the portions ofthe cache line(s) that the compressed data does not fill. For example,for a 128 Byte cache line and compressed data of 64 Bytes, writing thecompressed data to the cache line may fill only about half of the cacheline. Receiving the compressed data from the memory 16 means that thetransaction may also include 64 Bytes of overfetch data to fill in the128 Byte cache line. Using the supplemental write command, rather thanreceiving the 64 Byte compressed data and the 64 Byte overfetch data,the cache memory controller 300 may receive only the 64 Byte compresseddata from the memory 16. In this example, the data sent between thememory 16 and the cache memory controller 300 is half of what may betransmitted in conventional systems. Rather than receiving the overfetchdata from the memory 16, the cache memory controller 300 may fill in theremaining portions of the cache line(s) with supplemental data. Thus,the bandwidth necessary for transmitting data between the memory 16 andthe cache memory controller 300 may be reduced. Also, using constantvalues or a specified pattern to fill the remaining portions of thecache lines may reduce the power used to write to the remaining portionsas compared to the writing the random overfetch data. The constantvalues or pattern may also be used to identify this supplemental data asinvalid data without having to set an invalid or dirty indicator. In anaspect, since the cache memory controller 300 is responsible for fillingin the cache line(s), it may be aware that the supplemental data isinvalid and may avoid setting the invalid or dirty indicator, or mayignore the invalid or dirty bit.

Similarly, for a write cache memory access request using thesupplemental write command from the processor 14, the cache memorycontroller 300 may handle writing constant values, a pattern of values,or random values to fill the remaining portions of the cache lines. Assuch, similar power saving benefits may occur. As discussed above, thesupplemental data may be used to identify invalid data without having toset an invalid or dirty indicator. Also, the cache memory controller 300may be aware that the supplemental data is invalid and may avoid settingthe invalid or dirty indicator, or may ignore the invalid or dirty bit.

In an aspect, for a write cache memory access request the processor 14may implement power aware padding. As will be discussed in more detailbelow, the processor 14 may identify that compressed data of the writecache memory access request may not fill the cache line(s) for which thecompressed data is addressed. The processor 14 may also identify wherein relation to the compressed data may there be unfilled portions of thecache line(s), and the size of the unfiled portions. The processor 14may add padding data, such as constant data values or a pattern of datavalues, to the compressed data before sending the write cache memoryaccess request. The processor 14 may send the combined data of thecompressed data and padding data together as part of the write cachememory access request. The cache memory controller 300 may receivepadded compressed data and treat the padded compressed data as any otherdata of a write cache memory access request which fills the cacheline(s) to which the data is addressed. For example, for a 128 Bytecache line and compressed data of 64 Bytes, writing the compressed datato the cache line may fill only about half of the cache line. Theprocessor 14, having compressed the data, thus being aware of the sizeand/or compression ratio of the compressed data, and being aware of theamount of data that may be sent to the cache memory 302 over acommunication bus and/or the size of the cache lines of the cache memory302, may determine whether the size of the compressed data may not filla cache line. With this information, the processor core 14 may determineto add padding data to the compressed data to fill the cache line(s) inthe cache memory 302 to which the compressed data is addressed forwriting. The padding information, being one or more constant data valuesor pattern of data values may also result in power savings because ofthe reduced amount of energy required to transmit and write the paddingdata to the cache memory 302.

FIGS. 4 and 5 illustrate a portion of a cache memory including a cacheline 400, 402, 404, or cache block 500, 502, 504 made up of at least apair of cache lines 508, 510 storing compressed data 408, 512 inaccordance with an aspect. As illustrated in these examples, each cacheline 400, 402, 404, 508, 510 may store compressed data that does notcompletely fill all of the cache lines 400, 402, 404, 508, 510 leavingunfilled portions 410, 514. As described above, unfilled portions 410,514 may be filled using the supplemental write command or power awarepadding. Thus, the unfilled portions 410, 514 may be filled withsupplemental data or padding data.

The aspects illustrated in FIG. 4 and FIG. 5 illustrate commonsituations in which the supplemental write command and power awarepadding may be implemented.

Referring to FIG. 4 and continuing with the previous examples, theexample cache lines 400, 402, 404, 508, 510 are each 128 Bytes. In theillustrated example the compressed data 408 is 64 Bytes. Since thecompressed data 408 is half of the size of the cache lines 400, 402, 404where it may be stored on the cache memory, 64 Bytes unfilled portions410 of the cache lines 400, 402, 404 will be created. The 64 Byteunfilled portions 410 of each cache line 400, 402, 404 may be contiguousor in two segments when the compressed data 408 is not aligned witheither end of the cache line 404.

Referring to FIG. 5, the pair of cache lines 508, 510 may each be 128Byte and together form the cache blocks 500, 502, 504 of 256 Bytes. Thecompressed data 512 in the cache blocks 500, 502, 504 may be larger thana single cache line 508, 510, but smaller than a combination of cachelines 508, 510. For example, the compressed data 512 may be 192 Bytes.Since the compressed data 512 in this example is three quarters of thesize of the cache blocks 500, 502, 504 (or the combination of cachelines 508, 510) where it is stored on the cache memory, unfilledportions 514 of the cache lines 508, 510 are created. The unfilledportions 514 for each cache line 508, 510 may equate to 64 Bytes ofspace, which may be contiguous or in two portions when the compresseddata 512 is not aligned with either end of the cache lines 508, 510 inthe cache block 504.

In various aspects the cache memory controller may fill the unfilledportions 410, 514 with supplemental data. The cache memory controllermay write supplemental data, including constant data values, a patternof data values, or random values, to the unfilled portions 410, 514. Thesupplemental data may be written to the unfilled portions 410, 514before, concurrently with, or after writing the compressed data 408, 512to the cache lines 400, 402, 404, 508, 510. The cache memory controllermay write supplemental data to the unfilled portions 410, 514 inresponse to receiving the supplemental write command from the processor.

The processor may fill the unfilled portions 410, 514 with padding data.The processor may combine the compressed data 408, 512 with paddingdata, including constant data values or a pattern of data values. Theprocessor may determine, based on the size of the compressed data and/orthe compression ratio, and the size of the cache lines of the cachememory, that the compressed data may not fill the cache lines 400, 402,404, 508, 510. The padding data may be written to the unfilled portions410, 514 concurrently with writing the compressed data 408, 512 to thecache lines 400, 402, 404, 508, 510. The cache memory controller maywrite padding data to the unfilled portions 410, 514 in response toreceiving the write cache memory access request for compressed data withpadding data from the processor.

In various aspects, the memory cache memory controller and/or theprocessor may provide full or limited support for the supplemental writecommand or power aware padding. In an aspect, support may includefilling the unfilled portions 410, 514 regardless of where thecompressed data 408, 512 is located in the cache lines 400, 402, 404,508, 510. In various aspects, support may include filling the unfilledportions 410, 514 when the compressed data 408, 512 is aligned with thebeginning and/or end of the cache lines 400, 402, 404, 508, 510.

FIG. 6 illustrates a process and signal of a read cache memory accessrequest with supplemental write command for retrieving compressed datafrom the cache memory 302 in accordance with an aspect. The signals600-620 for executing the read cache memory access request withsupplemental write command may be transmitted between the processor 14,the cache memory controller 300, the cache memory 302, the memorycontroller 304, and the memory 16 via one or more communication bussesand various other components of the SoC. The processor 14 may send theread cache memory access request with supplemental write command signal600 to the cache memory controller 300. Receiving the read cache memoryaccess request with supplemental write command signal 600, the cachememory controller 300 may send a retrieval signal 602 for the datarequested by the read cache memory access request with supplementalwrite command to the cache memory 300. A cache miss signal 604 from thecache memory 302 to the cache memory controller 300 may indicate to thecache memory controller 300 that the requested data is not found in thecache. Although the processor 14 may expect the requested data to befound in the cache memory 302, the data may not be found for variousreasons. For example, the requested data may be evicted prior toattempts to retrieve it based on various data eviction schemes that maybe specified for the cache memory 302.

The cache memory controller 300 may issue a read memory access requestsignal 606 to the memory controller 304 in an attempt to retrieve therequested data backed up on the memory 16. Cache memory 302 is avolatile memory for storing relatively small amounts of data and programinstructions for relatively fast access, compared to the memory 16 orthe storage device discussed above. The cache memory 302 may includedata and program instructions that are duplicates of those stored in thememory 16 or the storage device. In an aspect, the data in the cachememory 302 may be altered and stored back to the memory 16 or thestorage device according to various schemes to maintain the integrity ofthe data in the computing device. Thus, the memory access controller 300may know where in the memory 16 the missing requested data from thecache memory 302 may be backed up. Receiving the memory access requestsignal 606, the memory controller 304 may send a retrieval signal 608for the data requested by the read cache memory access request withsupplemental write command to the memory 16. The memory 16 may providethe requested data in a return signal 610 to the memory controller 304excluding any overfetch data. The requested data may be forwarded to thecache memory controller 300 in another return signal 612 by the memorycontroller 304.

Receiving the return signal 612 with the requested data, the cachememory controller 300 may send a write signal 614 with the requesteddata to the cache memory 302 to write the requested data to a specifiedaddress/cache line(s). The cache memory controller 300 may also send asupplemental write signal 616 with supplemental data to the cache memory302 to write the supplemental data to a specified address/cache line(s)where the writing of the requested data creates unfilled portions in thecache lines. In an aspect, the order of the write signal 614 with therequested data and the write signal 616 with supplemental data may bereversed. In an aspect, the write signal 614 with the requested data andthe write signal 616 with supplemental data may be combined and sent asa single signal, or sent concurrently. The cache memory 302 may send thecache memory controller 300 a return signal 618 with the requested data,and the cache memory controller 300 may forward the requested data tothe processor 14 by a return signal 620. In an aspect the return signal618 with the requested data and the return signal 620 may exclude thesupplemental data of the cache lines from which the requested data maybe retrieved.

FIG. 7 illustrates a process and signals of a write cache memory accessrequest with supplemental write command for writing compressed data to acache memory 302 in accordance with an aspect. The signals 700-712 forexecuting the write cache memory access request with supplemental writecommand may be transmitted between the processor 14, the cache memorycontroller 300, the cache memory 302, the memory controller 304, and thememory 16, via one or more communication busses and various othercomponents of the SoC. The processor 14 may send the write cache memoryaccess request with supplemental write command signal 700 to the cachememory controller 300. Receiving the write cache memory access requestwith supplemental write command signal 600, the cache memory controller300 may send a send a write signal 702 with the requested data to thecache memory 302 to write the requested data to a specifiedaddress/cache line(s). The cache memory controller 300 may also send asupplemental write signal 704 with supplemental data to the cache memory302 to write the supplemental data to a specified address/cache line(s)where the writing of the requested data creates unfilled portions in thecache lines. In an aspect, the order of the write signal 702 with therequested data and the write signal 704 with supplemental data may bereversed. In an aspect, the write signal 702 with the requested data andthe write signal 704 with supplemental data may be combined and sent asa single signal, or sent concurrently.

As described above, the data written to the cache memory 302 may bebacked up to the memory 16. In doing so, the cache memory controller 300may send a retrieval signal 706 for the requested data. In an aspect,the retrieval signal 706 for the requested data may be temporallyseparated from the write cache memory access request with a supplementalwrite command signal 700 such that one or more cache memory accessrequests may have occurred. Thus, the requested data in this instance isnamed as such to identify the data related to the write cache memoryaccess request with supplemental write command signal 700 even thoughthere may be no pending request from the processor 14 relating to therequested data. The cache memory 302 may send the cache memorycontroller 300 a return signal 708 with the requested data. The cachememory controller 300 may issue a write memory access request signal 710to the memory controller 304 to write the requested data the memory 16.In an aspect the return signal 708 with the requested data and the writememory access request signal 710 may exclude the supplemental data ofthe cache lines from which the requested data may be retrieved.Receiving the write memory access request signal 710 with the requesteddata, the memory access controller 304 may send a write signal 712 withthe requested data to the memory 16.

FIG. 8 illustrates a process and signals of a write cache memory accessrequest with power aware padding for writing compressed data to a cachememory 302 in accordance with an aspect. The signals 800-814 forexecuting the write cache memory access request with power aware paddingmay be transmitted between the processor 14, the cache memory controller300, the cache memory 302, the memory controller 304, and the memory 16,via one or more communication busses and various other components of theSoC. The processor 14 may compress 800 an amount of data for a writecache memory access request. The processor 14 may determine and combine802 the padding data to the compressed data to fill the cache line(s)for the write cache memory access request. The processor 14 may furthersend a write cache memory access request with power aware padding signal804 to the cache memory controller 300. The write cache memory accessrequest with power aware padding signal 804 may include requested dataincluding the compressed data combined with the padding data. Receivingthe write cache memory access request with power aware padding signal804, the cache memory controller 300 may send a write signal 806 withthe requested data to the cache memory 302 to write the requested datato a specified address/cache line(s).

As described above, the data written to the cache memory 302 may bebacked up to the memory 16. In doing so, the cache memory controller 300may send a retrieval signal 808 for the requested data. In an aspect,the retrieval signal 808 for the requested data may be temporallyseparated from the write cache memory access request with power awarepadding signal 804 such that one or more cache memory access requestsmay have occurred. Thus, the requested data in this instance is named assuch to identify the data related to the write cache memory accessrequest with power aware padding signal 804 even though there may be nopending request from the processor 14 relating to the requested data.The cache memory 302 may send the cache memory controller 300 a returnsignal 810 with the requested data. The cache memory controller 300 mayissue a write memory access request signal 812 to the memory controller304 to write the requested data the memory 16. In an aspect the returnsignal 810 with the requested data and the write memory access requestsignal 812 may include the padding data of the cache lines from whichthe requested data may be retrieved. Receiving the write memory accessrequest signal 812 with the requested data, the memory access controller304 may send a write signal 814 with the requested data to the memory16.

FIG. 9 illustrates an aspect method 900 for implementing cache memoryaccess requests with supplemental write commands for compressed data.The method 900 may be executed in a computing device using software,general purpose or dedicated hardware, such as the processor or cachememory controller, or a combination of software and hardware. In block902 the cache memory controller may receive a cache memory accessrequest for reading from or writing to the cache memory, including asupplemental write command. In an aspect, the processor may issue thecache memory access request with the supplemental write command inresponse to determining that the data requested in the cache memoryaccess request may not fill all of the cache lines to which it isaddressed. In an aspect the determination may be based on compresseddata of a size or compression ratio such that the compressed data maynot fill all of the cache lines to which it is addressed. In an aspect,the determination may be based on uncompressed data that may be toosmall to fill all of the cache lines to which it is addressed.

In determination block 904, the cache memory controller may determinewhether the compressed data fills the cache line(s) to which it isaddressed. The cache memory controller may be aware of the size of thecache lines of the cache memory and the addresses of each of the cachelines. Using this information, the cache memory controller may comparethe addresses and/or sizes of the cache lines and the compressed data todetermine whether the compressed data may fill the cache lines to whichit is addressed. In response to determining that the compressed datawill fill the cache lines to which it is addressed (i.e. determinationblock 904=“YES”), the cache memory controller may write the compresseddata to the cache memory as known in block 906.

In response to determining that the compressed data will not fill thecache lines to which it is addressed (i.e. determination block904=“NO”), the cache memory controller may determine whether the cachememory access request is for reading from or writing to the cache memoryin determination block 908. The cache memory access request may containan indication for instructing the cache memory controller to implementeither reading from or writing to the cache memory.

In response to determining that the cache memory access request is acache write request for writing to the cache memory (i.e. determinationblock 908=“WRITE”), the cache memory controller may determine thesupplemental data to write to the unfilled portions of the cache line(s)in block 910. As described above, the supplemental data may includeconstant data values (e.g., all “0”), a pattern of data values, orrandom data values. In an aspect, the supplemental data may bepredetermined either in software or hardware of the cache memorycontroller. In block 912, the cache memory controller may write thecompressed data to the cache memory at the cache lines to which it isaddressed. In block 914, the cache memory controller may write thesupplemental data to the cache memory to fill the unfilled portions ofthe cache lines to which the compressed data is addressed. In an aspect,the order of the write operations in blocks 912 and 914 may be reversed.In an aspect, the write operations in blocks 912 and 914 may be executedconcurrently.

In response to determining the cache memory access request is a cacheread request for reading from the cache memory (i.e. determination block908=“READ”), the cache memory controller may determine whether thecompressed data is located in the cache lines to which it is addressedin determination block 916. As discussed above, regardless of whetherthe processor expects to locate the compressed data at a certain addressin the cache memory, the compressed data may not be found at the certainaddress for various reasons, such as cache replacement schemes. Inresponse to determining that the compressed data is not located in thecache lines to which it is addressed, which is referred to as a cachemiss (i.e. determination block 916=“NO”), the cache memory controllermay retrieve the compressed data from the memory in block 918. Asdescribed above, the cache memory controller may issue a memory accessrequest to the memory access controller to retrieve the compressed datafrom the memory. Rather than retrieving the compressed data with theoverfetch data as is traditionally done, the cache memory controller mayrequest and receive only the compressed data from the memory.Transmitting only the compressed data between the memory and the cachememory controller, rather than the compressed data plus the overfetchdata, reduces the bandwidth requirements for memory access requestsresulting from cache misses.

In block 920, the cache memory access controller may determine thesupplemental data to write to the unfilled portions of the cache line(s)as in block 910 described above. In block 922 the cache memorycontroller may write the compressed data to the cache memory at thecache lines to which it is addressed as in block 912 described above. Inblock 924, the cache memory controller may write the compressed data tothe cache memory to fill the unfilled portions of the cache lines towhich the compressed data is addressed as in block 914 described above.In an aspect, the order of the write operations in blocks 922 and 924may be reversed. In an aspect, the write operations in blocks 922 and924 may be executed concurrently.

In block 926, the cache memory controller may return the compressed datato the processor in response to the read cache memory access request. Inresponse to determining that the compressed data is located in the cachelines to which it is addressed, which is known as a cache hit (i.e.determination block 916=“YES”), the cache memory controller may retrievethe compressed data from the cache memory in block 928. In block 926,the cache memory controller may return the compressed data to theprocessor in response to the read cache memory access request.

FIG. 10 illustrates an aspect method 1000 for implementing cache memoryaccess requests with power aware padding for compressed data. The method1000 may be executed in a computing device using software, generalpurpose or dedicated hardware, such as the processor or cache memorycontroller, or a combination of software and hardware. As noted above,the aspects herein are related in terms of compressed data forsimplicity of explanation; however, the aspect may also apply to datatoo small to fill one or more cache lines. In optional block 1002 theprocessor may compress data for a write cache memory access request. Indetermination block 1004, the processor may determine whether thecompressed data will fill the cache line(s) of the cache memory to whichthe processor may address the compressed data for storage. In an aspectthe determination may be based on compressed data of a size orcompression ratio such that the compressed data may not fill all of thecache lines to which it is addressed. In an aspect, the determinationmay be based on uncompressed data that may be too small to fill all ofthe cache lines to which it is addressed. In response to determiningthat the compressed data will fill the cache line(s) of the cache memoryto which the processor addresses the compressed data for storage (i.e.determination block 1004=“YES”), the processor may send a write cachememory access request for the compressed data as known.

In response to determining that the compressed data will not fill thecache line(s) of the cache memory to which the processor addresses thecompressed data for storage (i.e. determination block 1004=“NO”), theprocessor may determine padding data (e.g., constants, patterns of data,or random data) to combine with the compressed data such that thecombined data may fill the cache line(s) in block 1006. The padding datamay generally be determined in terms of reducing the power required totransmit and write the padding data to the cache memory and the memorycompared to using random data. The padding data may also be selected ascertain values or patterns may be ascribed meaning to the processor,cache memory controller, and/or memory controller, such as identifyingthe padding data as invalid data. In an aspect, the padding data may bepredetermined in software or hardware of the processor.

In block 1010, the processor may combine the compressed data and thepadding data. The combination may be executed in such a way that theaddressing in the cache memory for the compressed data may not bechanged and the padding data may be used to fill the cache lineaddresses around the compressed data. In an aspect, the combination mayalter the addressing of the compressed data to align the compressed datawith either the beginning or the end of the cache line(s), and thepadding data may be used to fill the cache line addresses after orbefore the compressed data in the cache line(s). In block 1012, theprocessor may send a write cache memory access request with the combineddata, including the compressed data and the padding data, to the cachememory controller for storing the combined data in the cache memory.

FIG. 11 illustrates an example mobile computing device suitable for usewith the various aspects. The mobile computing device 1100 may include aprocessor 1102 coupled to a touchscreen controller 1104 and an internalmemory 1106. The processor 1102 may be one or more multicore integratedcircuits designated for general or specific processing tasks. Theinternal memory 1106 may be volatile or non-volatile memory, and mayalso be secure and/or encrypted memory, or unsecure and/or unencryptedmemory, or any combination thereof. Examples of memory types which canbe leveraged include but are not limited to DDR, LPDDR, GDDR, WIDEIO,RAM, SRAM, DRAM, P-RAM, R-RAM, M-RAM, STT-RAM, and embedded DRAM. Thetouchscreen controller 1104 and the processor 1102 may also be coupledto a touchscreen panel 1112, such as a resistive-sensing touchscreen,capacitive-sensing touchscreen, infrared sensing touchscreen, etc.Additionally, the display of the computing device 1100 need not havetouch screen capability.

The mobile computing device 1100 may have one or more radio signaltransceivers 1108 (e.g., Peanut, Bluetooth, Zigbee, Wi-Fi, RF radio) andantennae 1110, for sending and receiving communications, coupled to eachother and/or to the processor 1102. The transceivers 1108 and antennae1110 may be used with the above-mentioned circuitry to implement thevarious wireless transmission protocol stacks and interfaces. The mobilecomputing device 1100 may include a cellular network wireless modem chip1116 that enables communication via a cellular network and is coupled tothe processor.

The mobile computing device 1100 may include a peripheral deviceconnection interface 1118 coupled to the processor 1102. The peripheraldevice connection interface 1118 may be singularly configured to acceptone type of connection, or may be configured to accept various types ofphysical and communication connections, common or proprietary, such asUSB, FireWire, Thunderbolt, or PCIe. The peripheral device connectioninterface 1118 may also be coupled to a similarly configured peripheraldevice connection port (not shown).

The mobile computing device 1100 may also include speakers 1114 forproviding audio outputs. The mobile computing device 1100 may alsoinclude a housing 1120, constructed of a plastic, metal, or acombination of materials, for containing all or some of the componentsdiscussed herein. The mobile computing device 1100 may include a powersource 1122 coupled to the processor 1102, such as a disposable orrechargeable battery. The rechargeable battery may also be coupled tothe peripheral device connection port to receive a charging current froma source external to the mobile computing device 1100. The mobilecomputing device 1100 may also include a physical button 1124 forreceiving user inputs. The mobile computing device 1100 may also includea power button 1126 for turning the mobile computing device 1100 on andoff.

The various aspects described above may also be implemented within avariety of mobile computing devices, such as a laptop computer 1200illustrated in FIG. 12. Many laptop computers include a touchpad touchsurface 1217 that serves as the computer's pointing device, and thus mayreceive drag, scroll, and flick gestures similar to those implemented oncomputing devices equipped with a touch screen display and describedabove. A laptop computer 1200 will typically include a processor 1211coupled to volatile memory 1212 and a large capacity nonvolatile memory,such as a disk drive 1213 of Flash memory. Additionally, the computer1200 may have one or more antenna 1208 for sending and receivingelectromagnetic radiation that may be connected to a wireless data linkand/or cellular telephone transceiver 1216 coupled to the processor1211. The computer 1200 may also include a floppy disc drive 1214 and acompact disc (CD) drive 1215 coupled to the processor 1211. In anotebook configuration, the computer housing includes the touchpad 1217,the keyboard 1218, and the display 1219 all coupled to the processor1211. Other configurations of the computing device may include acomputer mouse or trackball coupled to the processor (e.g., via a USBinput) as are well known, which may also be used in conjunction with thevarious aspects.

The various aspects may also be implemented in any of a variety ofcommercially available servers for compressing data in server cachememory. An example server 1300 is illustrated in FIG. 13. Such a server1300 typically includes one or more multi-core processor assemblies 1301coupled to volatile memory 1302 and a large capacity nonvolatile memory,such as a disk drive 1304. As illustrated in FIG. 13, multi-coreprocessor assemblies 1301 may be added to the server 1300 by insertingthem into the racks of the assembly. The server 1300 may also include afloppy disc drive, compact disc (CD) or DVD disc drive 1306 coupled tothe processor 1301. The server 1300 may also include network accessports 1303 coupled to the multi-core processor assemblies 1301 forestablishing network interface connections with a network 1305, such asa local area network coupled to other broadcast system computers andservers, the Internet, the public switched telephone network, and/or acellular data network (e.g., CDMA, TDMA, GSM, PCS, 3G, 4G, LTE, or anyother type of cellular data network).

Computer program code or “program code” for execution on a programmableprocessor for carrying out operations of the various aspects may bewritten in a high level programming language such as C, C++, C#,Smalltalk, Java, JavaScript, Visual Basic, a Structured Query Language(e.g., Transact-SQL), Perl, or in various other programming languages.Program code or programs stored on a computer readable storage medium asused in this application may refer to machine language code (such asobject code) whose format is understandable by a processor.

Many computing devices operating system kernels are organized into auser space (where non-privileged code runs) and a kernel space (whereprivileged code runs). This separation is of particular importance inAndroid and other general public license (GPL) environments in whichcode that is part of the kernel space must be GPL licensed, while coderunning in the user-space may not be GPL licensed. It should beunderstood that the various software components/modules discussed heremay be implemented in either the kernel space or the user space, unlessexpressly stated otherwise.

The foregoing method descriptions and the process flow diagrams areprovided merely as illustrative examples and are not intended to requireor imply that the operations of the various aspects must be performed inthe order presented. As will be appreciated by one of skill in the artthe order of operations in the foregoing aspects may be performed in anyorder. Words such as “thereafter,” “then,” “next,” etc. are not intendedto limit the order of the operations; these words are simply used toguide the reader through the description of the methods. Further, anyreference to claim elements in the singular, for example, using thearticles “a,” “an” or “the” is not to be construed as limiting theelement to the singular.

The various illustrative logical blocks, modules, circuits, andalgorithm operations described in connection with the various aspectsmay be implemented as electronic hardware, computer software, orcombinations of both. To clearly illustrate this interchangeability ofhardware and software, various illustrative components, blocks, modules,circuits, and operations have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentinvention.

The hardware used to implement the various illustrative logics, logicalblocks, modules, and circuits described in connection with the aspectsdisclosed herein may be implemented or performed with a general purposeprocessor, a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA) orother programmable logic device, discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. A general-purpose processor maybe a microprocessor, but, in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aprocessor may also be implemented as a combination of computing devices,e.g., a combination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration. Alternatively, some operations ormethods may be performed by circuitry that is specific to a givenfunction.

In one or more aspects, the functions described may be implemented inhardware, software, firmware, or any combination thereof. If implementedin software, the functions may be stored as one or more instructions orcode on a non-transitory computer-readable medium or a non-transitoryprocessor-readable medium. The operations of a method or algorithmdisclosed herein may be embodied in a processor-executable softwaremodule that may reside on a non-transitory computer-readable orprocessor-readable storage medium. Non-transitory computer-readable orprocessor-readable storage media may be any storage media that may beaccessed by a computer or a processor. By way of example but notlimitation, such non-transitory computer-readable or processor-readablemedia may include RAM, ROM, EEPROM, FLASH memory, CD-ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that may be used to store desired programcode in the form of instructions or data structures and that may beaccessed by a computer. Disk and disc, as used herein, includes compactdisc (CD), laser disc, optical disc, digital versatile disc (DVD),floppy disk, and blu-ray disc where disks usually reproduce datamagnetically, while discs reproduce data optically with lasers.Combinations of the above are also included within the scope ofnon-transitory computer-readable and processor-readable media.Additionally, the operations of a method or algorithm may reside as oneor any combination or set of codes and/or instructions on anon-transitory processor-readable medium and/or computer-readablemedium, which may be incorporated into a computer program product.

The preceding description of the disclosed aspects is provided to enableany person skilled in the art to make or use the present invention.Various modifications to these aspects will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other aspects without departing from the spirit or scope ofthe invention. Thus, the present invention is not intended to be limitedto the aspects shown herein but is to be accorded the widest scopeconsistent with the following claims and the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A method for executing cache memory accessrequests for data on a computing device, comprising: receiving, by acache memory controller from a processor, a cache memory access requestfor data smaller than a cache line to which the data is addressed in thecache memory access request; receiving, by the cache memory controllerfrom the processor, a supplemental write command associated with thereceived cache memory access request; determining whether the datarequested by the cache memory access request is smaller than a cacheline in response to receiving both the cache memory access request andthe supplemental write command; and writing supplemental data tounfilled portions of the cache line to which the data is addressed inthe cache memory access request.
 2. The method of claim 1, furthercomprising: determining whether the data is located in the cache line towhich the data is addressed in the cache memory access request;retrieving the data from a memory in response to determining that thedata is not located in the cache line to which the data is addressed;and writing the data to the cache line to which the data is addressedresulting in unfilled portions of the cache line; and ignoring a dirtybit of the cache line.
 3. The method of claim 1, wherein receiving thesupplemental write command associated with the received cache memoryaccess request comprises receiving an instruction directing the cachememory controller to write supplemental data to unfilled portions of thecache line.
 4. The method of claim 1, wherein receiving the supplementalwrite command associated with the received cache memory access requestcomprises: receiving a signal indicating the supplemental write command;and interpreting the signal by the cache memory controller causing thecache memory controller to write supplemental data to unfilled portionsof the cache line.
 5. The method of claim 1, wherein writingsupplemental data to unfilled portions of the cache line to which thedata is addressed in the cache memory access request comprises writingone of constant data values to unfilled portions of the cache line towhich the data is addressed.
 6. The method of claim 1, wherein writingsupplemental data to unfilled portions of the cache line to which thedata is addressed in the cache memory access request comprises writing apattern of data values to unfilled portions of the cache line to whichthe data is addressed.
 7. The method of claim 1, wherein writingsupplemental data to unfilled portions of the cache line to which thedata is addressed in the cache memory access request comprises writingrandom values to unfilled portions of the cache line to which the datais addressed.
 8. The method of claim 1 further comprising determiningwhether the data is smaller than a cache line using one of a size of thedata and a compression ratio of the data.
 9. A computing device,comprising: a processor; a cache memory controller communicativelyconnected to the processor; a cache memory communicatively connected tothe cache memory controller; a memory controller communicativelyconnected to the cache memory controller; and a memory communicativelyconnected to the memory controller, wherein the cache memory controlleris configured to perform operations comprising: receiving a cache memoryaccess request for data smaller than a cache line to which the data isaddressed in the cache memory access request; receiving, from theprocessor, a supplemental write command associated with the receivedcache memory access request; determining whether the data requested bythe cache memory access request is smaller than a cache line in responseto receiving both the cache memory access request and the supplementalwrite command; and writing, from the processor, supplemental data tounfilled portions of the cache line to which the data is addressed inthe cache memory access request.
 10. The computing device of claim 9,wherein the cache memory controller is configured to perform operationsfurther comprising: determining whether the data is located in the cacheline to which the data is addressed in the cache memory access request;retrieving the data from the memory in response to determining that thedata is not located in the cache line to which the data is addressed;writing the data to the cache line to which the data is addressedresulting in unfilled portions of the cache line; and ignoring a dirtybit of the cache line.
 11. The computing device of claim 9, wherein thecache memory controller is configured to perform operations such thatreceiving the supplemental write command associated with the receivedcache memory access request comprises receiving an instruction directingthe cache memory controller to write supplemental data to unfilledportions of the cache line.
 12. The computing device of claim 9, whereinthe cache memory controller is configured to perform operations suchthat receiving the supplemental write command associated with thereceived cache memory access request comprises: receiving a signalindicating the supplemental write command; and interpreting the signalby the cache memory controller causing the cache memory controller towrite supplemental data to unfilled portions of the cache line.
 13. Thecomputing device of claim 9, wherein the cache memory controller isconfigured to perform operations such that writing supplemental data tounfilled portions of the cache line to which the data is addressed inthe cache memory access request comprises writing one of constant datavalues to unfilled portions of the cache line to which the data isaddressed.
 14. The computing device of claim 9, wherein the cache memorycontroller is configured to perform operations such that writingsupplemental data to unfilled portions of the cache line to which thedata is addressed in the cache memory access request comprises writing apattern of data values to unfilled portions of the cache line to whichthe data is addressed.
 15. The computing device of claim 9, wherein thecache memory controller is configured to perform operations such thatwriting supplemental data to unfilled portions of the cache line towhich the data is addressed in the cache memory access request compriseswriting random values to unfilled portions of the cache line to whichthe data is addressed.
 16. The computing device of claim 9, wherein thecache memory controller is configured to perform operations furthercomprising determining whether the data is smaller than a cache lineusing one of a size of the data and a compression ratio of the data. 17.A non-transitory processor-readable medium having stored thereonprocessor-executable instructions configured to cause a processor and acache memory controller to perform operations comprising: receiving, bythe cache memory controller from the processor, a cache memory accessrequest for data smaller than a cache line to which the data isaddressed in the cache memory access request; receiving, by the cachememory controller from the processor, a supplemental write commandassociated with the received cache memory access request; determiningwhether the data requested by the cache memory access request is smallerthan a cache line in response to receiving both the cache memory accessrequest and the supplemental write command; and writing supplementaldata to unfilled portions of the cache line to which the data isaddressed in the cache memory access request.
 18. The non-transitoryprocessor-readable medium of claim 17, wherein the storedprocessor-executable instructions are configured to cause the processorand the cache memory controller to perform operations furthercomprising: determining whether the data is located in the cache line towhich the data is addressed in the cache memory access request;retrieving the data from a memory in response to determining that thedata is not located in the cache line to which the data is addressed;and writing the data to the cache line to which the data is addressedresulting in unfilled portions of the cache line; and ignoring a dirtybit of the cache line.
 19. The non-transitory processor-readable mediumof claim 17, wherein the stored processor-executable instructions areconfigured to cause the processor and the cache memory controller toperform operations such that receiving the supplemental write commandassociated with the received cache memory access request comprisesreceiving an instruction directing the cache memory controller to writesupplemental data to unfilled portions of the cache line.
 20. Thenon-transitory processor-readable medium of claim 17, wherein the storedprocessor-executable instructions are configured to cause the processorand the cache memory controller to perform operations such thatreceiving the supplemental write command associated with the receivedcache memory access request comprises: receiving a signal indicating thesupplemental write command; and interpreting the signal by the cachememory controller causing the cache memory controller to writesupplemental data to unfilled portions of the cache line.
 21. Thenon-transitory processor-readable medium of claim 17, wherein the storedprocessor-executable instructions are configured to cause the processorand the cache memory controller to perform operations such that writingsupplemental data to unfilled portions of the cache line to which thedata is addressed in the cache memory access request comprises writingone of constant data values to unfilled portions of the cache line towhich the data is addressed.
 22. The non-transitory processor-readablemedium of claim 17, wherein the stored processor-executable instructionsare configured to cause the processor and the cache memory controller toperform operations such that writing supplemental data to unfilledportions of the cache line to which the data is addressed in the cachememory access request comprises writing a pattern of data values tounfilled portions of the cache line to which the data is addressed. 23.The non-transitory processor-readable medium of claim 17, wherein thestored processor-executable instructions are configured to cause theprocessor and the cache memory controller to perform operations suchthat writing supplemental data to unfilled portions of the cache line towhich the data is addressed in the cache memory access request compriseswriting random values to unfilled portions of the cache line to whichthe data is addressed.
 24. A computing device, comprising: means forreceiving, by a cache memory controller from a processor, a cache memoryaccess request for data smaller than a cache line to which the data isaddressed in the cache memory access request; means for receiving, bythe cache memory controller from the processor, a supplemental writecommand associated with the received cache memory access request; meansfor determining whether the data requested by the cache memory accessrequest is smaller than a cache line in response to receiving both thecache memory access request and the supplemental write command; andmeans for writing supplemental data to unfilled portions of the cacheline to which the data is addressed in the cache memory access request.25. The computing device of claim 24, further comprising: means fordetermining whether the data is located in the cache line to which thedata is addressed in the cache memory access request; means forretrieving the data from a memory in response to determining that thedata is not located in the cache line to which the data is addressed;and means for writing the data to the cache line to which the data isaddressed resulting in unfilled portions of the cache line; and meansfor ignoring a dirty bit of the cache line.
 26. The computing device ofclaim 24, wherein means for receiving the supplemental write commandassociated with the received cache memory access request comprises meansfor receiving an instruction directing the cache memory controller towrite supplemental data to unfilled portions of the cache line.
 27. Thecomputing device of claim 24, wherein means for receiving thesupplemental write command associated with the received cache memoryaccess request comprises: means for receiving a signal indicating thesupplemental write command; and means for interpreting the signal by thecache memory controller causing the cache memory controller to writesupplemental data to unfilled portions of the cache line.
 28. Thecomputing device of claim 24, wherein means for writing supplementaldata to unfilled portions of the cache line to which the data isaddressed in the cache memory access request comprises means for writingone of constant data values to unfilled portions of the cache line towhich the data is addressed.
 29. The computing device of claim 24,wherein means for writing supplemental data to unfilled portions of thecache line to which the data is addressed in the cache memory accessrequest comprises means for writing a pattern of data values to unfilledportions of the cache line to which the data is addressed.
 30. Thecomputing device of claim 24, wherein means for writing supplementaldata to unfilled portions of the cache line to which the data isaddressed in the cache memory access request comprises means for writingrandom values to unfilled portions of the cache line to which the datais addressed.